Gold according to the periodic table. Gold - a chemical element: a complete description

Gold- an element of group 11 (according to the outdated classification - a side subgroup of the first group), the sixth period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 79. It is designated by the symbol Au (lat. Aurum). The simple substance gold is a noble metal of yellow color. CAS registration number: 7440-57-5.

Pure gold is a soft yellow metal. The reddish hue of some gold products, such as coins, is given by impurities of other metals, in particular copper. In thin films, gold appears green. Gold has high thermal conductivity and low electrical resistance.
Gold is a very heavy metal: the density of pure gold is 19.321 g/cm³ (a ball of pure gold with a diameter of 46.237 mm has a mass of 1 kg). Among metals, it ranks sixth in density: after osmium, iridium, rhenium, platinum and plutonium. The high density of gold makes it easier to mine. The simplest technological processes, such as, for example, washing at locks, can provide a very high degree of recovery of gold from the washed rock.

79 element of the periodic table Gold is a very soft metal: hardness on the Mohs scale ~ 2.5, according to Brinell 220-250 MPa (comparable to the hardness of a nail).

Gold is also highly ductile: it can be forged into sheets up to ~0.1 µm thick (gold leaf); with such a thickness, gold is translucent and in reflected light it has a yellow color, in transmitted light it is colored bluish-greenish in addition to yellow. Gold can be drawn into wire with a linear density of up to 2 mg/m.
The melting point of gold is 1064.18 °C (1337.33 K), it boils at 2856 °C (3129 K). The density of liquid gold is less than that of solid gold, and is 17 g/cm3 at the melting point. Liquid gold is quite volatile, and actively evaporates long before the boiling point.
The linear coefficient of thermal expansion is 14.2 10-6 K−1 (at 25 °C). Thermal conductivity - 320 W / m K, specific heat capacity - 129 J / (kg K), electrical resistivity - 0.023 Ohm mm2 / m.

Electronegativity according to Pauling - 2.4. The electron affinity energy is 2.8 eV; atomic radius 0.144 nm, ionic radii: Аu+ 0.151 nm (coordination number 6), Аu3+ 0.082 nm (4), 0.099 nm (6).

gold in the chemical periodic table and got the best answer

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Gold is the 79th element of the Periodic Table of Elements, a precious yellow metal.
Gold is the most inert metal, standing in the series of voltages to the right of all other metals, under normal conditions it does not react with most acids and does not form oxides, due to which it was classified as a noble metal, unlike ordinary metals, which are easily destroyed under the influence of environment. Then the ability of aqua regia to dissolve gold was discovered, which shook the confidence in its inertness.
Of the pure acids, gold dissolves only in hot concentrated selenic acid:
2Au + 6H2SeO4 = Au2(SeO4)3 + 3H2SeO3 + 3H2O
Gold reacts relatively easily with oxygen and other oxidizing agents with the participation of complexing agents. So, in aqueous solutions of cyanides, with the access of oxygen, gold dissolves, forming cyanoaurates:
4Au + 8CN− + 2H2O + O2 → 4− + 4OH−
In the case of a reaction with chlorine, the possibility of complexation also greatly facilitates the course of the reaction: if gold reacts with dry chlorine at ~200 °C to form gold (III) chloride, then gold dissolves in an aqueous solution (aqua regia) with the formation of chloraurate ion already at room temperature. temperature:
2Au + 3Cl2 + 2Cl− → 2−
Gold easily reacts with liquid bromine and its solutions in water and organic solvents, giving the tribromide AuBr3.
Gold reacts with fluorine in the temperature range of 300–400°C, at lower temperatures the reaction does not occur, and at higher temperatures gold fluorides decompose.
Gold also dissolves in mercury, effectively forming a fusible alloy (amalgam).
Gold / Aurum (Au),Gold,Or
Atomic number 79
Appearance Soft viscous
malleable yellow
metal
Atom properties
Atomic mass
(molar mass) 196.96654 a.u. e.m. (g/mol)
Atom radius 146 pm
Ionization energy
(first electron) 889.3 (9.22) kJ/mol (eV)
Electronic configuration 4f14 5d10 6s

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Ruthenium, rhodium, palladium, osmium, iridium and sometimes rhenium. This name was given to the above metals due to their high chemical resistance. Gold has been highly valued throughout the world since ancient times. Its special value is evidenced by the fact that any medieval alchemist considered the goal of his life to obtain gold from other substances, most often it was used as a starting material. Legends exist that some, such as Nicolas Flamel, even succeeded.

Gold and its history

Incredibly, gold is the very first metal known to mankind! Its discovery dates back to the Neolithic era, i.e. about 11,000 years ago! Gold was widely used in all ancient civilizations, it was called the "king of metals" and denoted by the same hieroglyph as the sun. There are archaeological finds of gold jewelry that were made in the third millennium BC. e.
The whole history of mankind is closely connected with gold. The vast majority of wars before the use of oil was fought precisely because of this noble metal. As Goethe aptly noted in his Faust: "People die for metal!" Gold was one of the prerequisites for the Great geographical discoveries, i.e. period in history during which Europeans discovered new continents and sea routes to Africa, America, Asia and Oceania. In the 15th century, due to the economic crisis and constant wars, there was an acute shortage of precious metals for making money, so the royal courts were looking for new trading markets, and, most importantly, places where there was a lot of cheap gold. This is how we learned about the existence of America and Australia!

Golden Mask (Thailand)

Initially, mankind used gold only for making jewelry and luxury goods, but gradually began to serve as a medium of exchange, i.e. began to function as money. In this capacity, gold was used as early as 1500 BC. e. in China and Egypt. In the state of Lydia (the territory of modern Turkey), which possessed huge deposits of gold, gold coins were minted for the first time. The amount of gold in this state exceeded all the reserves of this metal available at that time in other states so much that the name of the Lydian king Croesus became a proverb and became synonymous with untold wealth. They say "Rich as Croesus."
In the Middle Ages and later, South America was the main source of gold. But at the beginning of the 19th century, large deposits of gold were discovered in the Urals and Siberia, so for several decades Russia ranked first in its production. Later, rich deposits were discovered in Australia and South Africa. Thus, there was a sharp increase in gold production. Until that time, along with gold from precious metals, silver was used to produce coins. But the influx of gold from the aforementioned countries ensured the displacement of silver. Therefore, by the beginning of the 20th century, gold had established itself as a standard. By itself, gold is rarely used as a material for coins, because. it is very soft and ductile (1 gram of gold can be stretched for 1 km), and therefore quickly worn out, it is mainly used in the form of alloys that increase the hardness of the material. But at first, the coins were minted from pure gold and one of the ways to check the coin was to try it “by the tooth”, the coin was clamped with teeth, if a decent trace remained, it was believed that the coin was not fake.

Gold coins of the world

Distribution of gold in nature

Gold is not very common on our planet, but it is not uncommon either, its content in the lithosphere is about 4.3 10 -7%, and in one liter sea ​​water it contains about 4·10 -9 g. Some amount of gold is in the soil, from there it is obtained by plants. Corn is an excellent source of natural gold for human nutrition, this plant has the ability to concentrate it in itself. Gold mining is an extremely difficult task, which is why it has such a high price. As geologists say, "gold loves loneliness", because. most often it is found in the form of nuggets, i.e. it is in the ore in its pure form. Only in extremely rare cases there are compounds of gold with bismuth and selenium. A very small amount of it is found in igneous rocks, in hardened lava. But it costs even more work to extract gold from them, and its content is very low. Therefore, the method of extraction from igneous rocks is not used due to its unprofitability.
The main gold reserves are concentrated in Russia, South Africa and Canada.

Chemical properties of gold

Most often, gold has a valence equal to +1 or +3. It is a highly corrosive resistant metal. Gold is absolutely not subject to oxidation, i.e. oxygen under normal conditions has no effect on it. However, if gold is heated above 100°C, a very thin oxide film forms on its surface, which does not disappear even when cooled. At a temperature of 20 °C, the film thickness is approximately 0.000001 mm. Sulfur, phosphorus, hydrogen and nitrogen do not react with gold.
Gold is not affected by acids. But only if they act on it separately. The only pure acid in which gold can be dissolved is hot concentrated selenic acid H 2 SeO 4 . At room temperature, the noble metal dissolves in the so-called "royal vodka", i.e. mixtures of nitric acid + hydrochloric acid. Also, under normal conditions, gold is very susceptible to the effects of solutions of potassium iodide and iodine.

The use of gold

Since ancient times, gold has been used in jewelry, as an item of luxury and power. Due to its exceptional plasticity and malleability, jewelers can create real works of art from this metal. In industry, gold is used in the form of alloys with other metals. Firstly, it increases the strength of the alloy, and secondly, it reduces the cost of production. The gold content of an alloy is called "fineness", which is expressed as some kind of whole standard number. For example, a kilogram of an alloy of 750 samples contains 750 grams of gold. The remaining 250 are other impurities. Therefore, the higher the sample, the higher the gold content in the alloy. There is a standard for this content: 375, 500, 585, 750, 900, 916, 958 samples are used.

Do you know that?

It takes a ton of gold ore to craft one gold ring!

Gold watch - a sign of wealth

In other industries, gold is used for various purposes in chemical and petrochemical industries, in energy and electronics, in aviation and space technology. This noble metal is used wherever corrosion is by no means undesirable. It has also been widely used in medicine since time immemorial due to its resistance to oxidation. Mummies with gold crowns of teeth have been found in Egyptian tombs. Currently, high-strength gold alloys are used for dentures and crowns. In addition, gold is used in pharmacology. Here, various compounds of the precious metal are used, which are included both in the preparations and are used separately. Gold threads are used in cosmetology, here they help skin rejuvenation.

Do you know that?

In the Japanese city of Suwa, there is a factory where gold is mined from the ashes left after burning industrial waste! Moreover, in this ashes, its content is greater than in any gold mine. This fact is explained by the fact that in the city there are a lot of factories producing electronics, in which this noble metal is widely used.

Summarize. Gold has retained its investment, industrial, jewelry and medical purpose for several millennia, and this trend is unlikely to stop in the foreseeable future. Gold will always be the personification of luxury and wealth!

GOLD (chemical element) GOLD (chemical element)

GOLD (lat. Aurum ) , Au (read "aurum"), a chemical element with atomic number 79, atomic mass 196.9665. Known since ancient times. In nature, one stable isotope is 197 Au. Configuration of the outer and pre-outer electron shells 5 s 2 p 6 d 10 6s one . It is located in the IB group and the 6th period of the periodic system, belongs to the noble metals. Oxidation states 0, +1, +3, +5 (valencies from I, III, V).
The metallic radius of the gold atom is 0.137 nm, the radius of the Au + ion is 0.151 nm for the coordination number 6, the Au 3+ ion is 0.084 nm and 0.099 nm for the coordination numbers 4 and 6. Ionization energies Au 0 - Au + - Au 2+ - Au 3 + are respectively equal to 9.23, 20.5 and 30.47 eV. Electronegativity according to Pauling (cm. PAULING Linus) 2,4.
Being in nature
The content in the earth's crust is 4.3 10 -7% by weight, in the water of the seas and oceans is less than 5 10 -6% mg / l. Refers to scattered elements. More than 20 minerals are known, of which the main one is native gold (electrum, cuprous, palladium, bismuth gold). Large nuggets are extremely rare and, as a rule, have nominal names. Chemical compounds of gold are rare in nature, mainly tellurides - caleverite AuTe 2 , krennerite (Au,Ag)Te 2 and others. Gold can be present as an impurity in various sulfide minerals: pyrite (cm. PYRITE), chalcopyrite (cm. chalcopyrite), sphalerite (cm. sphalerite) and others.
Modern methods of chemical analysis make it possible to detect the presence of trace amounts of Au in plant and animal organisms, in wines and cognacs, in mineral waters and in sea water.
Discovery history
Gold has been known to mankind since ancient times. Perhaps it was the first metal that man met. There is evidence of gold mining and the manufacture of products from it in Ancient Egypt (4100-3900 BC), India and Indo-China (2000-1500 BC), where money, expensive jewelry, works of art were made from it. cult and art.
Receipt
The sources of gold in its industrial production are ores and sands of gold placer and primary deposits, the gold content of which is 5-15 g per ton of source material, as well as intermediate products (0.5-3 g / t) of lead-zinc, copper, uranium and some other industries.
The process of extracting gold from placers is based on the difference in the densities of gold and sand. With the help of powerful jets of water, the crushed gold-bearing rock is transferred to a state suspended in water. The resulting pulp flows in the dredge along an inclined plane. In this case, heavy particles of gold settle, and grains of sand are carried away by water.
In another way, gold is extracted from ore by treating it with liquid mercury and getting a liquid alloy - an amalgam. Next, the amalgam is heated, the mercury evaporates, and the gold remains. The cyanide method of extracting gold from ores is also used. In this case, the gold ore is treated with a solution of sodium cyanide NaCN. In the presence of atmospheric oxygen, gold goes into solution:
4Au + O 2 + 8NaCN + 2H 2 O \u003d 4Na + 4NaOH
Next, the resulting solution of the gold complex is treated with zinc dust:
2Na + Zn \u003d Na 2 + NO + H 2 O
followed by selective precipitation of gold from solution, for example, using FeSO 4 .
Physical and chemical properties
Gold is a yellow metal with a face-centered cubic lattice ( a= 0.40786 nm). Melting point 1064.4 ° C, boiling point 2880 ° C, density 19.32 kg / dm 3. It has exceptional plasticity, thermal conductivity and electrical conductivity. A ball of gold with a diameter of 1 mm can be flattened into the thinnest sheet, translucent in a bluish-green color, with an area of ​​50 m 2. The thickness of the thinnest leaves of gold is 0.1 microns. The thinnest threads can be pulled out of gold.
Gold is stable in air and water. With oxygen (cm. OXYGEN), nitrogen (cm. NITROGEN), hydrogen (cm. HYDROGEN), phosphorus (cm. PHOSPHORUS), antimony (cm. ANTIMONY) and carbon (cm. CARBON) does not interact directly. Antimonide AuSb 2 and gold phosphide Au 2 P 3 are obtained indirectly.
In the series of standard potentials, gold is located to the right of hydrogen, therefore it does not react with non-oxidizing acids. Soluble in hot selenic acid:
2Au + 6H 2 SeO 4 = Au 2 (SeO 4) 3 + 3H 2 SeO 3 + 3H 2 O,
in concentrated hydrochloric acid when passed through a solution of chlorine:
2Au + 3Cl 2 + 2HCl = 2H
With careful evaporation of the resulting solution, yellow crystals of chloroauric acid HAuCl 4 3H 2 O can be obtained.
With halogens (cm. HALOGENS) without heating in the absence of moisture, gold does not react. When gold powder is heated with halogens or with xenon difluoride, gold halides are formed:
2Au + 3Cl 2 \u003d 2AuCl 3,
2Au + 3XeF 2 = 2AuF 3 + 3Xe
Only AuCl 3 and AuBr 3 are soluble in water, consisting of dimeric molecules:
The thermal decomposition of hexafluoraurates (V), for example, O 2 + - yielded gold fluorides AuF 5 and AuF 7 . They can also be obtained by oxidizing gold or its trifluoride with KrF 2 and XeF 6 .
The gold monohalides AuCl, AuBr, and AuI are formed by heating the corresponding higher halides in vacuum. When heated, they either decompose:
2AuCl \u003d 2Au + Cl 2
or disproportionate:
3AuBr = AuBr 3 + 2Au.
Gold compounds are unstable and hydrolyze in aqueous solutions, easily reducing to metal.
Gold (III) hydroxide Au (OH) 3 is formed by adding alkali or Mg (OH) 2 to a solution of H:
H + 2Mg(OH) 2 = Au(OH) 3 Ї + 2MgCl 2 + H 2 O
When heated, Au (OH) 3 easily dehydrates, forming gold (III) oxide:
2Au(OH) 3 \u003d Au 2 O 3 + 3H 2 O
Gold (III) hydroxide exhibits amphoteric properties, reacting with solutions of acids and alkalis:
Au (OH) 3 + 4HCl \u003d H + 3H 2 O,
Au(OH) 3 + NaOH = Na
Other oxygen compounds of gold are unstable and easily form explosive mixtures. The compound of gold oxide (III) with ammonia Au 2 O 3 4NH 3 - "explosive gold", explodes when heated.
During the recovery of gold from dilute solutions of its salts, as well as during the electrical spraying of gold in water, a stable colloidal solution of gold is formed:
2AuCl 3 + 3SnCl 2 = 3SnCl 4 + 2Au
The color of colloidal solutions of gold depends on the degree of dispersion of gold particles, and the intensity of their concentration. Gold particles in solution are always negatively charged.
Application
Gold and its alloys are used for the manufacture of jewelry, coins, medals, dentures, parts of chemical equipment, electrical contacts and wires, microelectronic products, for cladding pipes in the chemical industry, in the production of solders, catalysts, watches, for coloring glasses, and for making feathers. for fountain pens, coatings on metal surfaces. Usually gold is used in an alloy with silver or palladium (white gold; also called an alloy of gold with platinum and other metals). The gold content in the alloy is designated by the state hallmark. Gold 583 is an alloy with 58.3% gold by weight. See also Gold (in economics) (cm. GOLD (in economics)).
Physiological action
Some gold compounds are toxic, accumulate in the kidneys, liver, spleen and hypothalamus, which can lead to organic diseases and dermatitis, stomatitis, thrombocytopenia.

encyclopedic Dictionary. 2009 .

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- (French Chlore, German Chlor, English Chlorine) an element from the group of halides; its sign is Cl; atomic weight 35.451 [According to Clarke's calculation of Stas's data.] at O ​​= 16; a particle of Cl 2, which corresponds well to its densities found by Bunsen and Regnault with respect to ... ...

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Gold (English Gold, French Or, German Gold) is one of the seven metals of antiquity. It is generally believed that gold was the first metal that man met in the Stone Age due to its distribution in its native state. The special properties of gold - heaviness, brilliance, inoxidability, malleability, malleability - explain why it has been used since ancient times, mainly for the manufacture of jewelry and partly for weapons. Golden items for various purposes have been found by archaeologists in cultural layers dating back to the 4th and even the 5th millennium BC, i.e. to the Neolithic period. In the III and II millennia BC. e. gold was already widespread in Egypt, Mesopotamia, India, China, from ancient times it was known as a precious metal to the peoples of the American and European continents. Gold, from which the oldest jewelry is made, is impure, it contains significant impurities of silver, copper and other metals. Only in the VI century. BC e. in Egypt, almost pure gold appeared (99.8%). In the era of the Middle Kingdom, the development of Nubian gold deposits (Nubia, or Ethiopia of antiquity) began. This is where the ancient Egyptian name for gold, Nub, came from. In Mesopotamia, gold mining on a large scale was carried out already in the 2nd millennium BC. e. The Babylonian name for gold - khure - shu (hurasu) has a distant resemblance to the ancient Greek word (chrysos), which is found in all ancient literary monuments. Perhaps this word comes from the name of the area where gold could come from. The Old Indian ayas (gold) was later used in other languages ​​for copper, which may be an indication of the prevalence of counterfeit gold in antiquity. Since ancient times, gold has been associated with the sun, called the solar metal or simply the sun (Sol). In Egyptian Hellenistic literature and among alchemists, the symbol of gold is a circle with a dot in the middle, i.e. the same as the symbol of the sun. Sometimes in Greek alchemical literature there is a symbol in the form of a circle with the image of a ray associated with it.

Gold, as the most precious metal, has long served as an exchange equivalent in trade, in connection with which methods have arisen for the manufacture of gold-like alloys based on copper. These methods were widely developed and disseminated and served as the basis for the emergence of alchemy. The main goal of alchemists was to find ways to transform (transmute) base metals into gold and silver. European alchemists, following in the footsteps of the Arabs, developed the theory of "perfect" or even "superperfect" gold, the addition of which to a base metal turns the latter into gold. In alchemical literature, there are many names of gold, usually encrypted: zaras (zaras), trikor (tricor), salt (Sol), sun (Sonir), secur (secur), senior (senior), etc. Some of them have Arabic origin, for example al-bahag (joy), hiti (cat droppings), ras (head, principle), su "a (beam), diya (light), alam (peace).

The Latin (Etruscan) name for gold is Aurum (Aurum, ancient ausom) meaning "yellow". This word is well compared with the ancient Roman aurora or ausosa (morning dawn, eastern country, East). According to Schroeder, the word gold among the peoples of Central Europe also means yellow: in ancient German - gulth, gelo, gelva, in Lithuanian - geltas, in Slavic - gold, in Finnish - kulda. Among some Siberian peoples, gold is called altun, among the ancient Persians - zarania (or zar), which is compared with the ancient Indian hyrania (more often, however, related to silver) and ancient Greek (heaven). The Armenian name for gold, oski, stands apart. Slavic gold, or gold, used since ancient times, is undoubtedly connected (contrary to Schroeder) with the ancient Indo-European Sol (sun), probably in the same way as Central European Gold (gelb) with Greek (sun).

Such a variety of names for gold testifies to the widespread acquaintance with it of various ancient peoples and tribes and to the crossing of names of different tribes. The derivative names of gold compounds currently used come from the Latin aurum, Russian "gold" and Greek.